Page 250 - Maxwell House

230 ANTENNA BASICS

receiving (Rx) antenna to catch backscattering signal. Note that such radar configurations or
more complex ones with multiple transmit and receiving antennas are an expensive but effective
way to detect stealth targets and build a passive missile approach warning systems for homeland
security, etc. Moreover, additional receivers may be passive and hence largely immune to
jamming. The bistatic radar equation is the logical extension of (5.67) that yields

2

Margin = − ∆
3 ⎫
2 2
(5.70)

�4 �
4 4 ∆ ⎬
� > �

⎭
Here all variables are in SI units, is the RCS measured in the direction of the receiving

antenna, and the subscripts t and r are corresponds to transmit and receive site, respectively.
5.3.5 Multiple Input Multiple Output (MIMO) Radar System
MIMO radar architecture is the emerging modern technology that employs the multiplicity of
different active and passive (i.e. just receiving the signals, no radiation) radars in one
synchronized system. Each transmitter
1 generates different and often correlated
signal waveforms that create a wide
variety of signals reflected from the
targets and received by antennas at the
different spots. The primary drivers of
2 MIMO superiority are the mentioned
signal diversity, the big separation
between MIMO radar elements and
extremely sophisticated signal
processing. Figure 5.3.5 illustrates the
3 simplified setup of MIMO radar.

Antennas 1 (blue ray), 2 (yellow ray)
Figure 5.3.5 Simplified set up of MIMO radar and 3 (green ray) illuminate the target
while three others are receiving
antennas to pick up and process all the scattered from the target echo signals marked by blue,

Figure 5.3.6 MIMO radio link